Tape library systems using tape media with large storage capacity are widely used for backing up large amount of data. Such a tape library system has a library device including a plurality of receiving slots which receives tape media, and a robot which transports the tape media from the receiving slots to a physical drive. In performing a backup process, for example, the robot of the library device extracts a tape medium from a receiving slot and mounts the extracted tape medium on the physical drive. Subsequently, data to be backed up is written into the tape medium via the physical drive. Accordingly, with the tape library system, operations such as mounting the tape medium take substantial time when performing the backup process.
Accordingly, there is recently proposed a virtual library system which uses a disk array capable of high-speed data access to omit the time taken for operations such as mounting the tape medium, achieving faster reading and writing of data. The virtual library system, having a virtual tape device with a disk array installed between a host computer and a library device, treats reading from and writing to a logical volume on the disk array as virtually reading from and writing to a tape medium. Data of the logical volume is written out to the tape medium of the library device by the virtual tape device at a certain timing from the disk array. Such write out to the tape medium is sometimes referred to as migration.
The above-mentioned logical volume and the logical drive having the logical volume mounted thereon are implemented on a disk array. Therefore, high-speed data reading and writing may be realized without a physical mounting operation. It goes without saying that using a disk array capable of accessing data faster than a tape medium may also shorten the time taken for the data read/write process.
In addition, the virtual tape device has a function of writing the data of the logical volume to a tape medium according to an instruction received from the host computer and allowing the tape medium to be ejected from the library device (referred to as an export function in the following). The export function is used when transporting the tape medium having the data of the logical volume written thereon to another center, for example, and causing a virtual tape device installed at the other center to read the tape medium and move the logical volume.
The tape medium to which the data of the logical volume is written is attached with label information relating to the identification information of the logical volume. For example, when reading data of a logical volume specified by the virtual tape device from a tape medium, the library device selects a desired tape medium, referring to the label information. When writing the data of the logical volume specified by the virtual tape device into a tape medium, the library device also selects a desired tape medium, referring to the label information. As a method of displaying the label information, a paper tape having the label information written thereon may be attached to the tape medium, for example.
There is proposed a method of sticking, to a storage medium, an electronic paper having numbers displayed thereon based on electrical signals. In addition, there is proposed an LTO (Linear Tape-Open) tape driving device having an LTO tape drive and an IC (Integrated Circuit) tag reader/writer. The LTO tape drive device, upon loading an LTO having a magnetic tape and an IC tag, writes data into the magnetic tape of the LTO, and also writes, into the IC tag, data-related information such as target identification number and content of backup data.
Please see, for example, Japanese Patent No. 4918940, Japanese Laid-Open Patent Publication No. 2003-331560, and Japanese Laid-Open Patent Publication No. 2006-323918.
Although the method of attaching a paper tape having the label information written thereon to the tape medium is simple, there may arise in the event of tape medium failure a task of manually reattaching the paper tape to a substitute tape medium. When the aforementioned LTO tape drive device is being used, a user who has recognized a failure of the tape medium performs a task of reloading another tape medium on the LTO tape drive device so that information is written into an IC tag of the other tape medium. However, writing data into the tape medium is interrupted while the user is performing the task, and therefore it takes long time for write out of data.